If your diesel doesn't start

crofts · 12th September 2011, 01:47

Unless you have another lead to the problem.
Check the in tank pump is running when switching on the ignition (Do not start). Runs for approx 30 seconds
If I/T pump is running, tap the UNDERBONNET PUMP, preferably while trying to start but not always essential
Tip. Car will start and run with just U/B pump if sufficient fuel in tank. Usually results in U/B pump failing short term if I/T pump is not replaced........however much fuel is in the tank.
It is one you can try yourself at no cost.
Am sure others will add or comment further.

ChestersDad · 13th September 2011, 21:52

Thank you for that Crofts - Ours is okay at the mo - inevitable on the diesels is it - at some point?

Dragrad · 13th September 2011, 22:31

To give the pumps a better life, always keep your tank well above a quarter full. Less strain on the pumps

FLYER · 13th September 2011, 22:32

Quote:

Originally Posted by Dragrad

To give the pumps a better life, always keep your tank well above a quarter full. Less strain on the pumps

correcto .

Mike Noc · 14th September 2011, 08:26

Can anyone explain why this should be?

All the pump failures I've seen posted where the pumps have been stripped down turn out to be due to commutator wear. The system is designed to equalise the levels in the tank, but even if the pumps were running dry this wouldn't affect the commutator.

The commutator/brush material combination is the weak point so these pumps will wear as a function of run time. When switched on they pump more or less the same amount of fuel whether the engine is running flat out or not running at all.

Has anyone had a pump fail due to impeller/pump housing wear?

Mike

Alan.F · 14th September 2011, 19:20

rarely let mine go below quarter of a tank

James.uk · 14th September 2011, 19:29

As the impeller only pumps diesel oil it is not going to wear much at all, except maybe the shaft bearings. but the commutators wear out on any elec motor no matter what they drive..

...

Mike Noc · 14th September 2011, 19:45

Yes James but on most electric motors that use brushes it is the brushes that wear out first. From what I have seen the brushes are hardly worn and the commutators have worn right through to the plastic beneath.

The thing is if the impellers were wearing then keeping them immersed in diesel would help. But as it's the commutators that are going I can't see any advantage in keeping the tank level above a quarter, unless the ITP has already failed, in which case its vital.

Mike

RPWC · 14th September 2011, 19:49

Quote:

Originally Posted by James.uk

As the impeller only pumps diesel oil it is not going to wear much at all, except maybe the shaft bearings. but the commutators wear out on any elec motor no matter what they drive..

...

What happenned to your trademark innit?

COLVERT · 14th September 2011, 20:16

Quote:

Originally Posted by Mike Noc

Yes James but on most electric motors that use brushes it is the brushes that wear out first. From what I have seen the brushes are hardly worn and the commutators have worn right through to the plastic beneath.

The thing is if the impellers were wearing then keeping them immersed in diesel would help. But as it's the commutators that are going I can't see any advantage in keeping the tank level above a quarter, unless the ITP has already failed, in which case its vital.

Mike

I think you will find that having the pump immersed in diesel helps to make it run cooler.
If the level drops to the extent the pump is no longer pumping diesel then the armature will speed up considerably and maybe this extra speed makes the brush to commutator connection start to arc.
( As the brushes bounce slightly )
This will generate heat which will damage the split ring commutator which is embeded in plastic !!!

Maybe . Lol

12th September 2011, 01:47	#1
crofts I really should get out more....... 2003 Rover 75 Conn. SE Auto Tourer 131 ps CDTi Join Date: Nov 2006 Location: Bristol Posts: 2,512 Thanks: 38 Thanked 67 Times in 55 Posts	If your diesel doesn't start Unless you have another lead to the problem. Check the in tank pump is running when switching on the ignition (Do not start). Runs for approx 30 seconds If I/T pump is running, tap the UNDERBONNET PUMP, preferably while trying to start but not always essential Tip. Car will start and run with just U/B pump if sufficient fuel in tank. Usually results in U/B pump failing short term if I/T pump is not replaced........however much fuel is in the tank. It is one you can try yourself at no cost. Am sure others will add or comment further. __________________ Rover 75 CDTi SE Connoisseur Tourer (2003) In desirable STARLIGHT SILVER (now restored to it's former glory with all the chrome !)

13th September 2011, 21:52	#2
ChestersDad Still 75less :-( 1988 Defender 90 Join Date: Jun 2011 Location: Carmarthenshire Posts: 531 Thanks: 15 Thanked 93 Times in 37 Posts	Thank you for that Crofts - Ours is okay at the mo - inevitable on the diesels is it - at some point? __________________ Don't save for the future as someone else will lose it for you!

13th September 2011, 22:31	#3
Dragrad This is my second home *None DROWNED** Join Date: Aug 2007 Location: Cardigan Posts: 33,339 Thanks: 1,257 Thanked 1,664 Times in 1,081 Posts	To give the pumps a better life, always keep your tank well above a quarter full. Less strain on the pumps __________________ Andrew Ich Dien Problem solving is... lateral thinking SEARCH FIRST ...ASK LATER...

14th September 2011, 19:20	#6
Alan.F Gets stuck in MG ZT 1.8 Turbo Join Date: Jul 2010 Location: Bolton Posts: 623 Thanks: 32 Thanked 32 Times in 16 Posts	rarely let mine go below quarter of a tank __________________

14th September 2011, 19:45	#8
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Yes James but on most electric motors that use brushes it is the brushes that wear out first. From what I have seen the brushes are hardly worn and the commutators have worn right through to the plastic beneath. The thing is if the impellers were wearing then keeping them immersed in diesel would help. But as it's the commutators that are going I can't see any advantage in keeping the tank level above a quarter, unless the ITP has already failed, in which case its vital. Mike Last edited by Mike Noc; 14th September 2011 at 19:49..

14th September 2011, 08:26	#5
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Can anyone explain why this should be? All the pump failures I've seen posted where the pumps have been stripped down turn out to be due to commutator wear. The system is designed to equalise the levels in the tank, but even if the pumps were running dry this wouldn't affect the commutator. The commutator/brush material combination is the weak point so these pumps will wear as a function of run time. When switched on they pump more or less the same amount of fuel whether the engine is running flat out or not running at all. Has anyone had a pump fail due to impeller/pump housing wear? Mike

14th September 2011, 19:29	#7
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	As the impeller only pumps diesel oil it is not going to wear much at all, except maybe the shaft bearings. but the commutators wear out on any elec motor no matter what they drive.. ...